See my comment here for a workaround that got it working for me https://github.com/brave/brave-browser/issues/20395#issuecomment-1932836420
Also, SUPER BIG thanks for creating this thread and being persistent about this. I’ve had this issue for months and finally got annoyed enough to search for https://www.google.com/search?q=brave+cmd+shift+a+search+tabs+is+off+screen+mac and this was the first result, and it gave me enough hope to tinker enough to find the workaround!
